1. Put a baking sheet on the middle shelf of the oven and heat the oven to 475ºF. Spray a 12-inch tart pan with removable bottom or a 12-inch pizza pan with butter-flavored nonstick cooking spray. Combine the potatoes, half the scallions, half the Parmesan and half the pepper in a large bowl. Stir in half the eggs and mix until well blended.

2. Spread the potato mixture evenly on the bottom and up the sides of the pan. Put the tart on the preheated baking sheet and bake for 10 minutes or until golden brown. Remove from the oven. Reduce the oven temperature to 375ºF. Meanwhile, heat the oil in a large skillet over high heat; add the mushrooms and sauté for 5 minutes. Remove from the heat. Stir in the feta, milk, thyme and the remaining scallions, Parmesan, pepper and eggs.

3. Pour the mushroom mixture into the potato crust. Bake for 10 to 15 minutes or until set.